An illuminated board

Abstract

 The illuminated board consists of a rectangular transparent wedge-formed slab (3) which at one face is covered by an opalescent front panel (2) and at the other face by a reflecting, preferably white, rear panel (4).
When the broad end face (9) on the wedge is illuminated all light will, in an evenly distributed fashion, be directed to the front panel (2) which has a low degree of opalescence and therefore presents it­self as a brilliantly illuminated surface.
The construction makes for a lower energy con­sumption and a less bulky construction than convention­al illuminated boards used as sign boards and as illuminated tables in the graphic industries and in draftsmens's offices.

Description

[0001] This invention relates to an illuminated board for use in connection with advertisement boards and illumin­ated tables such as drawing boards used in the graphic industries and by draftsmen.

[0002] The purpose of the present invention is to bring about the illuminated surface of advertisement boards, traffic sign boards, illuminated tables such as drawing boards and shop signs at a lower energy consumption and in a less bulky construction than in the case of the hitherto known systems.

[0003] The solution according to the invention regarding an illuminated board comprising one or more light sources and a front panel consists in that the illuminated board comprises a transparent substantially rectangular wedge-­formed slab having two substantially triangular basis faces and a front face, a rear face and a broad end face, the said one or more light sources being mounted at the broad end face of the wedge, an opalescent front panel covering the front face and a light-reflecting rear panel covering the rear face of the wedge.

[0004] "Opalescent" is to be understood as "milky". The manufacturers of boards normally make use of front panels having varying degrees of opalescence. A high degree of opalescence means a low degree of translucence.

[0005] The construction of the invention brings about an illuminated board in which substantially all of the light source's light without any loss is directed towards the front plate which can be chosen with a low degree of opalescence; i.e. a high degree of translucence so that the loss of light will be low.

[0006] In comparison to this, in a conventional illuminated board the light source is simply covered by the front panel which must be opalescent enough for concealing the shape of the light source or sources. Typically, according to the invention it will be possible to use front panels having a light transmittance of 75% compared to existing sign board systems which make use of front panels having a light transmittance of 25-50%.

[0007] In the present invention, not only will there be no need for concealing the light source by choosing a high degree of opalescence and a corresponding high loss of light energy, but the thickness of the illuminated board can be kept as low as that of the broad end face of the wedge or of the light source.

[0008] Experiments have led to the conclusion that the following features give an especially satisfactory board:
- The reflecting rear panel produces a diffusion of the light and is preferably of white colour.
- The front panel and the rear panel are mounted parallel to their respective faces at a distance of approx. 5 mm.
- The light sources are situated on a line which is parallel to the longitudinal axis of the broad end face of the wedge. Preferably luminous tubes are used as light sources because they optimally illuminate all of the broad end face of the wedge.
- The light sources are screened to the exterior so as to illuminate exclusively the broad end face of the wedge. The light source or sources may advantageously be mounted at the top of the rear panel which may continue into a U-shaped profile which serves the purpose of screening the light source of sources. The electrical supply is preferably the public current supply.
- The wedge-formed slab has a wedge angle of 1-4°, preferably about 2.5°.

[0009] The invention will be more fully explained in the following, reference being had to the drawing in which

Fig. 1 is a plan view of an embodiment of an illuminated board according to the in­vention, the size being 1. 5 meters x 0.5 meter,

Fig. 2 is a side-view of the illuminated board according to the invention,

Fig. 3 is a plan view showing an embodiment of the current supply (luminous tube embodiment),

Fig. 4 is an optical path diagram for the wedge, the front panel and the re­flecting rear panel, and

Fig. 5 is a perspective view of the rect­angular wedge with front panel and reflecting rear panel.

[0010] Fig. 2 shows an illuminated board according to the invention. The illuminated board consisting of a rect­angular transparent wedge-formed slab 3, an opalescent front panel 2, a reflecting rear panel 4 having prefer­ably white colour and a light source 5 in the form of a luminous tube which is screened by a U-formed profile 1.

[0011] The wedge 3 may be made of acryl and in one embodi­ment the dimensions are 150 x 50 cm² and the thickness or width of the end face 9 adjacent the light source is about 26 mm.

[0012] The narrow end face of the wedge, substantially an edge, has a width of 2 mm. The luminous tube 5 is placed on a line parallel to the longitudinal direction of the broad end face 9 of the wedge and fig. 3, in which the wedge and the front panel have been omitted, shows the electrical connection in which 7 is a coil and 8 is a starter. The latter two components may be situat­ed behind the reflector but may also be placed complete­ly outside the illuminated board.

[0013] The following is a description of the optical features of the illuminated board according to the in­vention.

[0014] Fig. 4 shows the wedge 3, viewed from the side, hav­ing a front panel 2, a reflecting rear panel 4 and a light source 5.

[0015] When a beam of light arrives from the light source to the broad end face 9 of the wedge it will, due to the angle of the wedge, be reflected at increasing angles of incidence and deflection until the angle of incidence is so great that the light will leave the wedge at either the front face or the rear face. By examination of the beam A it will be seen that this beam is re­flected at the top face, is directed through the bottom face, is reflected by the reflecting rear face and passes upwards through the wedge striking the front panel which is therefore illuminated. Beams B and C are examples of beams which arrive at the bottom face, are reflected upwards to the top face and are reflected again and finally leave the front face and arrive at the front panel which is illuminated.

Claims

1. An illuminated board for use as a sign board or an illuminated table such as a drawing board com­prising one or more light sources (5) and a front panel (2), characterized by the fact that the illuminated board comprises a substantially rectangular transparent wedge-formed slab (3) having two substan­tially triangular basis faces and a front face, a rear face and a broad end face (9), the said one or more light sources (5) being mounted at the board end face (9) of the wedge, an opalescent front panel (2) covering the front face and a light-reflecting rear panel (4) covering the rear face of the wedge.

2. Illuminated board according to claim 1, characterized by the fact that the reflect­ing rear panel (4) produces light diffusion.

3. Illuminated board according to claims 1-2, characterized by the fact that the reflect­ing rear panel (4) is white.

4. Illuminated board according to claims 1-3, characterized by the fact that the panels (2 and 4) are mounted parallel to the respective faces at a distance of approx. 5 mm.

5. Illuminated board according to claims 1-4, characterized by the fact that the light sources are situated on a line which is parallel to the longitudinal axis of the broad end face (9) of the wedge.

6. Illuminated board according to claims 1-5, characterized by the fact that the light sources are screened to the exterior so as to illuminate exclusively the broad end face (9) of the wedge.

7. Illuminated board according to claims 1-6, characterized by the fact that the trans­parent wedge-formed slab (3) has a wedge angle of 1-4°, preferably about 2.5°.

Drawing